The colorimetric determination of thorium using 1-(o-arsonophenylazo)-2-naphthol-3:6-disulphonic acid

A method is described for tin; determination of thorium in milligram quantities using 1-(o arsunophenylazo)-2-naplithol-3:6-disulphonic acid (APANS) with a precision of 0.5%. An account. of the interferences to be expected from some common ions is given and the method is employed in the determination of thorium in monazite following an oxalate seperation.